The present invention is in the general field of animal farming, especially poultry farming and relates particularly to controlled feeding of animals to improve their resistance to heat stress.
The demand for meat and eggs, including poultry and poultry eggs, especially chickens and chicken eggs has expanded considerably over the last decade. The poultry industry has grown from a home industry to a large scale manufacturing industry in which thousands of chickens and tens of thousands of eggs are produced daily at single poultry farms or egg laying installations. Some eggs are produced for eating and some eggs are produced for hatching. One problem with such large scale egg producing in high summer temperatures. Animals are highly susceptible to heat stress. Poultry laying hens are particularly vulnerable. As temperatures rise egg production decreases significantly.
Hens under heat stress not only produce fewer eggs and poorer quality eggs, but suffer a high mortality rate.
Extremely high temperatures and high temperature-high humidity conditions can have a devastating effect on the animal kingdom. Animals such as poultry, swine and canines, in particular, suffer because they have no sweat glands to provide cooling relief. Other animals that do have sweating capabilities suffer when high humidity conditions prevent adequate evaporation rates to allow sweating to be effective.
In modern production facilities for animal production of meat, milk and eggs the animals are kept largely in confinement and must be provided the proper environment for control of their body temperatures. These environments may become uncontrollable when there are severe heat waves.
With poultry, relatively short periods of time at temperatures above about 94.degree. F. will cause the temperature control mechanism in the body to malfunction and lead to brain damage and subsequent death. In the case of swine, confined management systems usually have thermostatically controlled sprinkling systems to wet the hogs to provide evaporative cooling when temperatures exceed 85.degree. F.; this need for cooling is commonly identified with age old associations of hogs and water holes. The panting of dogs during hot weather is their attempt to move as much air through their lungs for heat exchange and cooling.
We have found that the inclusion of zeolite, especially zeolite A in the diets of animals will help them endure or resist the ill effects that are associated with excessive heat conditions. Laboratory studies with laying hens indicated that zeolite A will result in improved performance when included in their diets as measured by reduced mortality, maintenance of egg weight, egg production rate, eggshell quality, and body weight.
It is therefore the primary object of the present invention to provide a diet for animals which effectively reduces heat stress in the animals.
It is an especially important object of the present invention to provide a diet for poultry which substantially reduces heat stress in the poultry.
It is another important object of the present invention to provide a means for inhibiting or effectively reducing heat stress in animals by adding a small amount of zeolite A to the diet of the animals regularly fed to the animals during high temperatures without any deleterious effect on the food value of the animals or animal products.
We have previously discovered that the strength of poultry eggs can be substantially enhanced by adding a small amount of zeolite A to the diet of the laying poultry.
In addition to increasing eggshell strength in laying hens as described in our U.S. Pat. No. 4,556,564, improving feed utilization efficiency in poultry and larger egg size as described in our U.S. Pat. No. 4,610,882, decreasing the mortality rate of poultry as described in our U.S. Pat. No. 4,610,883, and increasing the bone strength of animals, including humans, as set forth in our copending U.S. application Ser. No. 801,596, as a result of our continuing studies it has been discovered that the regular feeding of small amounts of zeolite A to poultry produces the following positive results:
1. Calmer birds, reduced activity (layers) PA0 2. Extended lay cycle duration (layers and broiler breeders) PA0 3. Reduced condemnation (broilers) PA0 4. Improved feathering (broilers) PA0 1. Improved resistance to heat stress, a multifaceted benefit PA0 2. Improved lean/fat ratio in the edible carcass
The advantages of larger eggs, extended lay cycles and reduced condemnations are self-evident. Calmer birds produce more, less deformed eggs and lay with greater regularity. Stress is a highly negative factor among laying hens. Improved feathering correlates with healthier and stronger birds.
More recently, our studies have discovered the following positive results:
Poultry are highly subject to heat stress. As temperatures rise, egg production decreases significantly, birds eat less feed, their body temperatures rise, they lose body weight, they lay smaller eggs of poorer shell quality, and they incur higher mortality rates. Birds regularly fed zeolite A are dramatically less susceptible to heat stress.
With the increased desirability of less fat in a human diet, it has become more and more important that the meat of poultry raised for food have a high lean content and a low fat content.
Zeolites are crystalline, hydrated aluminosilicates of alkali and alkaline earth cations, having infinite, three-dimensional structures.
Zeolites consist basically of a three-dimensional framework of SiO.sub.4 and AlO.sub.4 tetrahedra. The tetrahedra are crosslinked by the sharing of oxygen atoms so that the ratio of oxygen atoms to the total of the aluminum and silicon atoms is equal to two or O/(Al+Si)=2. The electrovalence of each tetrahedra containing aluminum is balanced by the inclusion in the crystal of a cation, for example, a sodium ion. This balance may be expressed by the formula Al/Na=1. The spaces between the tetrahedra are occupied by water molecules prior to dehydration.
Zeolite A may be distinguished from other zeolites and silicates on the basis of their composition and X-ray powder diffraction patterns and certain physical characteristics. The X-ray patterns for these zeolites are described below. The composition and density are among the characteristics which have been found to be important in identifying these zeolites.
The basic formula for all crystalline sodium zeolites may be represented as follows: EQU Na.sub.2 O.Al.sub.2 O.sub.3.xSiO.sub.2.yH.sub.2 O
In general, a particular crystalline zeolite will have values for "x" and "y" that fall in a definite range. The value "x" for a particular zeolite will vary somewhat since the aluminum atoms and the silicon atoms occupy essentially equivalent positions in the lattice. Minor variations in the relative number of these atoms do not significantly alter the crystal structure or physical properties of the zeolite. For zeolite A, the "x" value normally falls within the range 1.85.+-.0.5.
The value for "y" is not necessarily an invariant for all samples of zeolites. This is true because various exchangeable ions are of different size, and, since there is no major change in the crystal lattice dimensions upon ion exchange, the space available in the pores of the zeolite to accommodate water molecules varies.
The average value for "y" for zeolite A is 5.1. The formula for zeolite A may be written as follows: EQU 1.0.+-.0.2Na.sub.2 O.Al.sub.2 O.sub.3.1.85.+-.0.5SiO.sub.2.yH.sub.2 O
In the formula, "y" may be any value up to 6.
An ideal zeolite A has the following formula: EQU (NaAlSiO.sub.4).sub.12.27H.sub.2 O
Among the ways of identifying zeolites and distinguishing them from other zeolites and other crystalline substances, the X-ray powder diffraction pattern has been found to be a useful tool. In obtaining the X-ray powder diffraction patterns, standard techniques are employed. The radiation is the K.alpha. doublet of copper and a Geiger counter spectrometer or a suitable radiation detector with a strip chart pen recorder is used. The peak heights, I, and the positions as a function of 2.theta. where .theta. is the Bragg angle, are read from a spectrometer chart or accumulated in computer memory. From these, the relative intensities, 100 I/I.sub.o, where I.sub.o is the intensity of the strongest line or peak and d the interplanar spacing in angstroms corresponding to the recorded lines are calculated.
X-ray powder diffraction data for a sodium zeolite A are given in Table I.
TABLE I ______________________________________ X-RAY DIFFRACTION PATTERN FOR ZEOLITE A 100 I h.sup.2 + k.sup.2 + 1.sup.2 d (.ANG.) I.sub.o ______________________________________ 1 12.29 100 2 8.71 70 3 7.11 35 4 6.15 2 5 5.51 25 6 5.03 2 8 4.36 6 9 4.107 35 10 3.895 2 11 3.714 50 13 3.417 16 14 3.293 45 16 3.078 2 17 2.987 55 18 2.904 10 20 2.754 12 21 2.688 4 22 2.626 20 24 2.515 6 25 2.464 4 26 2.414 &gt;1 27 2.371 3 29 2.289 1 30 2.249 3 32 2.177 7 33 2.144 10 34 2.113 3 35 2.083 4 36 2.053 9 41 1.924 7 42 1.901 4 44 2.858 2 45 1.837 3 49 1.759 2 50 1.743 13 53 1.692 6 54 1.676 2 55 1.661 2 57 1.632 4 59 1.604 6 ______________________________________
The more significant d values for zeolite A are given in Table III.
TABLE II ______________________________________ MOST SIGNIFICANT d VALUES FOR ZEOLITE A d Value of Reflection in .ANG. ______________________________________ 12.2 .+-. 0.2 8.7 .+-. 0.2 7.10 .+-. 0.15 5.50 .+-. 0.10 4.10 .+-. 0.10 3.70 .+-. 0.07 3.40 .+-. 0.06 3.29 .+-. 0.05 2.98 .+-. 0.05 2.62 .+-. 0.05 ______________________________________
Occasionally, additional lines not belonging to the pattern for the zeolite appear in a pattern along with the X-ray lines characteristic of that zeolite. This is an indication that one or more additional crystalline materials are mixed with the zeolite in the sample being tested. Small changes in line positions may also occur under these conditions. Such changes in no way hinder the identification of the X-ray patterns as belonging to the zeolite.
The particular X-ray technique and/or apparatus employed, the humidity, the temperature, the orientation of the powder crystals and other variables, all of which are well known and understood to those skilled in the art of X-ray crystallography or diffraction can cause some variations in the intensities and positions of the lines. These changes, even in those few instances where they become large, pose no problem to the skilled X-ray crystallographer in establishing identities. Thus, the X-ray data given herein to identify the lattice for a zeolite, are not to exclude those materials which, due to some variable mentioned or otherwise known to those skilled in the art, fail to show all of the lines, or show a few extra ones that are permissible in the cubic system of that zeolite, or show a slight shift in position of the lines, so as to give a slightly larger or smaller lattice parameter.
A simpler test described in "American Mineralogist," Vol. 28, page 545, 1943, permits a quick check of the silicon to aluminum ratio of the zeolite. According to the description of the test, zeolite minerals with a three-dimensional network that contains aluminum and silicon atoms in an atomic ratio of Al/Si=2/3=0.67, or greater, produce a gel when treated with hydrochloric acid. Zeolites having smaller aluminum to silicon ratios disintegrate in the presence of hydrochloric acid and precipitate silica. These tests were developed with natural zeolites and may vary slightly when applied to synthetic types.
U.S. Pat. No. 2,882,243 describes a process for making zeolite A comprising preparing a sodium-aluminum-silicate water mixture having an SiO.sub.2 :Al.sub.2 O.sub.3 mole ratio of from 0.5:1 to 1.5:1, and Na.sub.2 O/SiO.sub.2 mole ratio of from 0.8:1 to 3:1, and an H.sub.2 O/Na.sub.2 O mole ratio of from 35:1 to 200:1, maintaining the mixture at a temperature of from 20.degree. C. to 175.degree. C. until zeolite A is formed, and separating the zeolite A from the mother liquor.
Experiments have been in progress in Japan since 1965 on the use of natural zeolite minerals as dietary supplements for poultry, swine and cattle. Significant increases in body weight per unit of feed consumed and in the general health of the animals was reported (Minato, Hideo, Koatsugasu 5:536, 1968). Reductions in malodor were also noted.
Using clinoptilolite and mordenite from northern Japan, Onagi, T. (Rept. Yamagata Stock Raising Inst. 7, 1966) found that Leghorn chickens required less food and water and gained as much weight in a two-week trail as birds receiving a control diet. No adverse effects on health or mortality were noted. The foregoing Japanese experiments were reported by F. A. Mumpton and P. H. Fishman in the Journal of Animal Science, Vol. 45, No. 5 (1977) pp. 1188-1203.
U.S. Pat. No. 3,836,676 issued to Chukei Komakine in 1974 discloses the use of zeolites as adsorbent moisture of ferrous sulfate crystals in an odorless chicken feed comprising such crystals and chicken droppings. The results were said to be no less than those in the case where chickens were raised with ordinary feed.
Canadian Pat. No. 939,186 issued to White et al in 1974 discloses the use of zeolites having exchangeable cations as a feed component in the feeding of urea or biuret non-protein (NPR) compounds to ruminants, such as cattle, sheep and goats. Natural and synthetic as well as crystalline and non-crystalline zeolites are disclosed. Zeolites tested included natural zeolites, chabazite and clinoptilolite and synthetic zeolites X, Y, F, J, M, Z, and A. Zeolite F was by far the most outstanding and zeolite A was substantially ineffective.
An article by C. Y. Chung et al from Nongsa Sihom Youngu Pogo 1978, 20 (Livestock) pp. 77-83 discusses the effects of cation exchange capacity and particle size of zeolites on the growth, feed efficiency and feed materials utilizability of broilers or broiling size chickens. Supplementing the feed of the broilers with naturally occurring zeolites, such as clinoptilolite, some increase in body weight gain was determined. Chung et al also reported that earlier results at the Livestock Experiment Station (1974, 1975, 1976--Suweon, Korea) showed that no significant difference was observed when 1.5, 3, and 4.5 percent zeolite was added to chicken layer diets.
A study by H. S. Nakaue of feeding White Leghorn layers clinoptilolite, reported in 1981 Poultry Science 60: 944-949, disclosed no significant differences in eggshell strength between hens receiving the zeolite in their diet and hens not receiving the zeolite in their diet.
In a recent study at the University of Georgia, both broilers and layers were fed small amounts (about 2%) of clinoptilolite, a naturally occurring zeolite from Tilden, Tex. The eggshells from the hens receiving zeolite were slightly more flexible as measured by deformation, slightly less strong as measured by Instron breaking strength, and had a slightly lower specific gravity. The differences in eggshell quality were very small. This type of zeolite was ineffective in producing a stronger eggshell. An article written by Larry Vest and John Shutze entitled "The Influence of Feeding Zeolites to Poultry Under Field Conditions" summarizing the studies was presented at Zeo-Agriculture '82.
It is therefore an important object of the present invention to provide an improved diet for animals for reducing heat stress in animals, wherein a small amount of zeolite is added to the feed directly fed to the animals during periods of temperatures sufficiently high to cause heat stress in the animals.
It is a principal object of the invention to provide a diet for poultry wherein a small amount of zeolite is added to the feed regularly fed to the poultry during heat stress causing temperatures without causing a deleterious effect on the poultry or poultry product.
Another object of the invention is to provide an improved process for decreasing heat stress in poultry laying hens wherein an effective amount of zeolite, especially zeolite A, is added to the feed fed to the poultry laying hens during heat stress causing temperatures.
Still another object of the invention is to cost effectively increase production of foods from animals or animal products during periods of heat stress causing temperatures.
Yet a further object of the present invention is to increase or maintain the level of the egg production of poultry laying hens during high summer temperatures.
Other objects and advantages of the invention will be more fully understood from a reading of the description and claims hereinafter.